JPH04258348A - Continuous casting and rolling method for bar and wire rod - Google Patents

Abstract

PURPOSE:To further improve the product yield and the productivity by making concentrical circular groove type mold size coincide with the product of casting speed regulated with each mold radius by each cross sectional area of cast billet in all lines. CONSTITUTION:In a small cross section continuous casting device for molten metal 2 rotating a ring mold with endless groove opening an upper part in a horizontal direction, plural lines of groove molds are provided on concentric circles on a table and plural cast billets are cast at the same time and directly rolled. In the concentric circular groove mold size, at the time of using V (m/min) the casting speed regulated with each mold radius and S (m<2>) each cross section of the cast billet, the casting set so as to coincide with the product VS (m<3>/min) in all lines, is executed. By this method, integrated continuous rolling at the time of casting in multi-streams can be executed and trouble caused by the difference in casting speed between streams, can be eliminated and further, the stable casting of molten metal and rolling can be executed, and the product yield and the productivity can be improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to continuous casting of molten metal, mainly molten steel, and particularly to a continuous casting and rolling method using a horizontally rotating continuous casting apparatus for casting small-section slabs.

0002

2. Description of the Related Art There is a horizontal rotating groove type method for continuously casting small cross-section slabs. In this horizontal continuous casting method, one side of the cross section is
It is suitable for casting billets with a small cross section of about 0 to 100 mm square, and is characterized by low equipment costs and high productivity.For example, U.S. Patent No. 3284859, U.S. Patent No.
10 and Japanese Patent Publication No. 63-13785. U.S. Pat. No. 3,284,859 discloses a continuous casting apparatus that includes an annular rotary mold cooling mold having a ladder-shaped cross section, and in which the long side of the ladder faces a metal supply device. This mold is formed with a casting groove into which molten metal is supplied from a gate device. The mold is driven to rotate around a vertical axis.

[0003] In order to cool the molten metal poured into the mold, forced cooling devices are provided which are constituted by spray nozzles arranged approximately at right angles to the mold walls. The solidified slab is continuously drawn out of the casting groove from a point located 200-270° from the injection point and fed to a continuous mill device.

0004

In all of the above-disclosed examples, one slab is cast when a slab is cast using a groove-type horizontal rotary continuous casting machine, which is one-stream casting. on the other hand,
In order to improve casting productivity and reduce production costs, it is effective not only to perform casting but also to perform direct rolling using the sensible heat of casting. Furthermore, in order to further improve casting productivity, it is desirable to increase the casting speed or perform multi-stream casting using one rotary table. Of course, direct rolling is the most ideal manufacturing form even if it is multi-stream. Such a horizontal rotary continuous casting machine rotates a concave endless groove type in a horizontal plane, so when casting molten metal, it casts the molten metal in the opposite direction to the casting direction, with the molten metal injection point as the border. A molten metal backflow prevention weir (hereinafter referred to as
A dummy bar or a molten metal outflow prevention member (hereinafter referred to as a front weir) is used in the casting direction from the injection point. Therefore, casting is usually started by injecting molten metal into the initial molten metal injection space formed by the tail weir and the tip of the dummy bar or the front weir, and starting rotation when the molten metal level reaches the desired height. It will be done. The height of the slab is determined by the height of the molten metal surface, and is adjusted by balancing the injection amount and drawing speed. Of course, it is possible to carry out casting without the initial molten metal injection space being sufficiently filled with molten metal, but this is not advisable as it causes large fluctuations in the size of the slab and causes a decrease in yield and rolling failures. This basic casting configuration presents even more serious problems when multi-tooth-ream casting. In other words, in the case of concentric multi-stream casting using a mold rotation drive system, since the rotational speed is the same, the casting speed between the streams will be different on the outer and inner sides, making it difficult to keep the slab cross-sectional area the same. In this case, the production amount will differ between each stream. If direct rolling is performed at the same time as multi-stream casting, further mutual adjustment is required.

[0005]

[Means for Solving the Problems] The present invention provides a continuous casting apparatus for molten metal in which a mold having an endless grooved ring mold with an open upper part rotates in a horizontal direction.
When casting small cross-section slabs of about 0 to 100 mm square,
In order to maximize its characteristics of low equipment costs and high productivity, it is a casting and rolling method that allows for multi-stream casting and direct rolling, and solves the problems caused by differences in casting speed due to differences in mold radius. It is something to do.

That is, the gist of the present invention is that in a small-section continuous casting apparatus for molten metal in which a ring mold with an open top and an endless groove rotates horizontally, a plurality of rows of groove molds are formed concentrically on one table. to simultaneously cast and directly roll a plurality of slabs, especially when a plurality of slabs are cast simultaneously and directly rolled, and the size of the concentric groove mold is defined by the radius of each mold. Casting speed is V (m/min),
Let the cross-sectional area of each slab be S (m2), and its product VS (
m3/min) in all rows; a continuous casting machine for small cross-sections of molten metal in which an endless grooved ring mold with an open top rotates horizontally; When multiple rows of grooves are arranged concentrically and multiple slabs are simultaneously cast and directly rolled, the rolling equipment is used as a roll to reduce the slab speed difference caused by the difference in mold radius when rolling multiple slabs at the same time. Continuous casting and rolling method characterized by changing the diameter of the rolling roll and rolling with the circumferential speed matching the casting speed, and a casting and rolling method in which a rolling mill is provided to unify the slab size and/or the cross-sectional size is the same. A continuous casting and rolling method characterized by dry-pass rolling a slab with a small cross-sectional size until In the case where one or more rows of groove molds are arranged concentrically on one table and rolled directly after casting, a heating means is provided during the casting and rolling process to heat the slab to the rolling temperature and/or to maintain the slab at a high temperature. This is a continuous casting and rolling method characterized by the following.

[0007]

[Operation] The present invention will be explained in detail below with reference to the drawings. FIG. 1 is a plan view showing an outline of a horizontal rotary continuous casting apparatus using an endless groove rotary mold according to the present invention. Figure 2 shows
2 shows a cross section taken along the casting direction XX in FIG. 1. FIG. 3 is a sectional view in the casting direction XX when a casting dummy bar is used. FIG. 4 is a process diagram of simultaneous casting and direct rolling of two streams. FIG. 5 is a process diagram in which each slab is simultaneously rolled between streams in two-stream casting. FIG. 6 is an explanatory diagram of a rough rolling roll in the case of simultaneous rolling. FIG. 7 is a method diagram and a roll explanatory diagram for performing finish simultaneous rolling by performing empty pass rolling to compensate for the difference in slab speed due to different slab sizes in the case of simultaneous rolling. FIG. 8 shows a rolling process in which a dedicated rolling mill for sizing is provided at the front stage.

Next, FIG. 1(a) shows an embodiment of the present invention.
) will be described in detail. 1 is a molten metal ladle, 2 is a molten metal, 3 is a molten metal injection device, 4 is an intermediate container, 5 is an injection amount control means and an injection nozzle, 6 is an endless groove type rotary mold,
7 is a slab during solidification, 8 is a tail weir, 9 is a tail weir support means, 10 is a mold rotation means, 11 is a slab propulsion device, 12 is a slab propulsion device drive means, 13 is a knife edge holding means, 1
4 is a slab straightening roll pressing means, 15 is a slab straightening vertical roll, 16 is a slab detector, 17 is a slab straightening horizontal roll, 1
8 is a slab, 18a is an outside slab, 18b is an inside slab, 19
2 is a slab guide roll, 20 is a slab straightening horizontal roll, 21 is a slab detector, 22 is a cutting machine, 23 is a knife edge, 24 is a dummy bar, 25 is a dummy bar storage device, 26 is a slab pressing unit when dividing the dummy bar 27 is a dummy bar split swing frame, 28 is a roller table for carrying out, 29 is a roller table, 30 is an injection point, 31 is a scale removal means, 32 is a slab heating/warming means, 33 is a rolling roll, 34 is a product a cutting machine; 35 is a product cooling control means;
36 is a coiled product, 37 is a linear product, 38 is a simultaneous rolling roll, 39 is a rough rolling roll of different diameters, 44 is an empty pass rolling roll, and 50 is a dedicated sizing rolling roll.

FIG. 1(b) shows a cross section of the mold AA in FIG. 1(a). Mold cross-sections inevitably occur due to the casting speed and mold radius of each stream. Further, the production amount is defined by the casting speed V and the weir V·S of the mold cross-sectional area S. Therefore, when the cross-sectional area of the mold is the same, the production amount between streams differs depending on the difference in casting speed. Although there are few technical problems when an independent rolling mill is provided after casting, when multiple strands are rolled simultaneously, it is necessary to increase the cross-sectional area on the inner peripheral side of the mold to absorb the difference in casting speed. Figure 1(b)
) shows an example in which the inner mold is enlarged. The cross-sectional area of each stream can be easily determined by calculation. Now, the target production volume is Q (m3 /min), and the production volume of each stream is Q1.
, Q2, the mold rotation speed is N (rpm), the stream diameter is D1, D2 (m) (D1 > D2), the casting speed is V1, V2 (m/min), the mold cross-sectional area is S
1, S2 (m2), and pi.

V1 = πD1 N V2 = πD2 N Q1 = V1 S1 = πD1 NS1Q2 = V2
From the conditions of S2 = πD2 NS2Q = Q1 = Q2, the cross-sectional area is S2 = S1 (D1 /D2) Therefore, the cross-sectional area of the mold on the inner circumferential side S2 is D1 > D2
It is sufficient to increase the diameter according to the diameter ratio (D1/D2).

Next, the process of casting the molten metal 2 is shown in FIG.
This will be specifically shown using FIG. 2(a) and FIG. Molten metal 2 is injected from a ladle 1 into an intermediate container 4 using a molten metal injection device 3, and is injected into a mold groove 7 provided in an endless groove mold 6 via an injection amount control means and an injection nozzle 5. Inside the mold,
A tail weir 8 is provided, and the molten metal is cast by rotating clockwise on the paper, and as the solidification progresses, the cast pieces are separated into the outer circumferential side 18a and the inner circumferential side 18.
It solidifies in step b and becomes a slab. At this time, it is also effective to prevent quality deterioration by maintaining the area of the molten metal exposed to the atmosphere in a non-oxidizing atmosphere, if necessary. The molten metal is cooled preferentially from the side and bottom sides in the endless groove mold 7, and solidification progresses. Eventually, the upper surface side is also cooled mainly by radiation heat transfer and solidified to form a solidified shell, which reaches the slab propulsion device 11. The slab is
The propulsion device 11 applies propulsion force from the surroundings by the groove mold and the propulsion device, and sends it onto the knife edge 13,
Eventually, the slab straightening means 14 to 17 are reached. The slab 18 is straightened into a straight line by the following slab straightening means 19 to 21, and cut into a desired length by a cutting machine 22. Of course,
It is also possible to arrange a rolling mill downstream of the casting apparatus and to perform rolling directly after or without cutting. Figure 2 is similar to Figure 1 (a
) is a diagram illustrating the XX cross section of the slab, showing the straightening process of drawing the slab out of the mold.

FIG. 3 shows a method of dividing the cast slab using a dummy bar, taken along the line X--X. It is composed of a swing frame 27 for dividing dummy bars, a roll 26 for pressing slabs, a roller table 28, a dummy bar storage device 25, and the like. The slab is cast, and when the tip of the dummy bar reaches the dummy bar split swing frame 27, it is separated from the slab and stored. On the other hand, the slab goes straight through the roller table 29 for carrying out, is cut as necessary, and is carried out to the next process to become a slab of desired length. The dummy bar may be a link structure having two or more degrees of freedom, and there is no need to use any special material; it may be made of carbon steel or the like.

FIG. 4 is a diagram showing the casting and rolling process. In this process, rolling equipment is provided for each stream depending on the number of streams in the continuous casting machine. The molten metal injected from the injection point 30 solidifies as the mold 6 rotates, and becomes slabs on the outer peripheral side 18a and the inner peripheral side 18b. The cast slab is cut by a cutter 22 as necessary, then maintained at a high temperature by a slab heating/insulating means 32 as necessary, and continuously rolled into a rolled product by a rolling mill 33. The products are simultaneously improved in quality by a cooling control means 35 provided as needed, and manufactured into coiled products 36 and linear products 37. Cooling control means include rapid cooling such as water cooling, quenching, hot water cooling, spray cooling, annealing, tempering, lead bath treatment, high temperature transformation treatment, solution treatment,
It is intended for brewing, etc. Further, although not particularly limited, since the slab is in a high temperature state, it is effective to purify it as necessary using scale removing means 31, which is an oxide removing means, to improve product quality.

FIG. 5 shows a process in which a multi-strand slab is rolled by a rolling mill 38, with the aim of reducing equipment costs for rolling equipment. FIG. 6 shows a rough rolling roll when performing multi-strand simultaneous rolling. In the case of multi-strand casting, the speeds between the strands are different. Therefore,
Rough rolling roll 3 in which the roll diameter of the rolling mill is changed in the axial direction
9, the circumferential speeds are matched, and the inner circumferential side rolled material 40 and the outer circumferential side rolled material 41 are simultaneously rolled. On this occasion,
The production amount remains different between the inner and outer circumferences. FIG. 7 is a process diagram showing a method of performing simultaneous rolling without using rolling rolls of different diameters. This is applied when the difference in production volume, which is a drawback of multi-stream casting, is compensated for by changing the slab size and simultaneous rolling is performed. It is characterized by providing rolls that perform one or more stages of empty pass rolling or very light rolling. By this rolling, the inner circumferential slab, that is, the slab with a large cross section is preferentially rolled, and after the stage when the sizes of the strands are uniform, finish rolling is performed using rolling rolls of the same shape.

The shape of the rolling roll 38 is on the first stage side 44.
This is different on the finishing side 47. That is, the outer slab 18a is rolled at 46 in the first stage, and the inner slab 18b is rolled at 45. Thereafter, in finish rolling 47, both 48 and 49 are rolled to the same size. Changes in the cross-sectional area of the slab during this series of processes are shown on the outer circumferential side 42 and on the inner circumferential side 43. Rolling progresses from left to right in the paper, and finishing is performed under the same rolling conditions from the third stage onwards. Although this figure shows eight rolling stands, the number of rolling stands is of course not limited to this.

This method is particularly effective when there is not enough space between the strands to install a rolling mill. Figure 8
The concept is the same as that of FIG. 7, but it can be applied when there is sufficient space between the strands to install a rolling mill. In this case, a sizing rolling mill 50 is provided to equalize the size of the slab between the strands. The number of rolling mills is not particularly limited, and at least one or more rolling mills may be installed. Thereby, subsequent simultaneous rolling can be performed more reliably.

[0017]

[Example] Examples and comparative examples will be explained below. The metal component used for casting was the carbon steel shown below. That is, C is 0.
30-0.32% by weight, Si 0.3-0.32% by weight
, Mn is 0.98 to 1.02% by weight, P is 0.010% by weight or less, S is 0.015% by weight or less, and Al is 0.
046-0.050% by weight carbon steel.

The casting and rolling conditions are shown below. Casting was carried out using an endless groove type horizontal continuous casting machine, with an outer mold radius of 1500 mm.
(mm), outer casting size is 49 mm square, outer casting speed is 10.4 (m/min, 1.1 rpm), inner mold radius is 1000 (mm), inner casting size is 60 m.
m square, inner peripheral casting speed 7.0 (m/min, 1.1r
pm), 300 kg of molten steel was cast under the conditions of two-stream casting and a molten steel superheating degree of 36°C. Two-stream casting was used, boron nitride (BN) was used for the tail weir, and an 8-high continuous hot rolling mill and a winding device were arranged downstream of the casting machine. The final finished dimension is φ25 mm for both the inner and outer circumference of the slab. The material of the dummy bar was S10C. A molded body of Al2O3 fibers was used as the front weir. Further, the molten steel injection amount is controlled by a stopper system driven by a hydraulic cylinder.

Before the hot rolling mill, the slab temperature is maintained at 1150° C. by high-frequency induction heating. As a result of the experiment, the temperature of the slab reached 1130 to 1150°C before the heating device, so it was practically possible to secure the rolling temperature by applying only about 10 to 20 kW of power to the heating device. . As a result, integrated manufacturing from casting to products was performed and evaluated. If a rolling mill is provided for each strand,
The consistent yield of each casting to product is 99.
8% and the inner slab was 99.5%. The yield difference is
This is due to the difference in the size of the slab on the inner and outer circumferences, resulting in crop drop during casting. However, it is clear that the yield is at a high level on both the inner and outer circumferences. On the other hand, when both strands were rolled at the same time using one series of rolling mills, the rolling was carried out by making about three empty passes on the outer peripheral side. The product yield at this time was exactly the same as when each strand was rolled independently.

Next, when rolling with rolls of different diameters was carried out, the slab size was set to 49 mm square for both the inner and outer circumferences of the mold. In this case, the product yield was 99.6% or more. However, since rolling with different diameter rolls reduces the roundness accuracy due to its structure, the rolling reduction was increased in the earlier stages, and the rolling reduction was decreased in the finish rolling to improve the roundness accuracy. In other words, when manufacturing a product with a diameter of 25 mm from a 49 mm square,
The first 1st and 2nd stages, which correspond to rough rolling, are the 2nd rolling exit side with a rolling ratio (cross-sectional area ratio) of 2.1, and the middle 3rd and 4th stages are the 4th rolling exit side with a rolling ratio of 1.8, 5th and 6th stages. The finish rolling of the mesh is 1.2 on the 6th stage exit side.
The final finishing of the 7th and 8th stages was performed at 1.08 on the exit side of the 8th stage. As a result, the roundness is good and the roundness accuracy is 5.
Achieved 0 μm. It should be noted that such means are not special means of the method of the present invention, but are used to lower the processing rate in the finishing process and improve accuracy even in normal rolling. It goes without saying that this rolling with different diameter rolls can be applied without any problems even when the sizes of the slab on the inner and outer circumferences of the slab are changed in order to balance the production volume of each stream.

Furthermore, an example will be shown in which a special sizing mill for the inner slab is used during simultaneous rolling. The slab was 60 mm square on the inner circumferential side and 49 mm square on the outer circumferential side, and was used as a two-stage sizing rolling mill. In special sizing rolling, a rolling ratio of approximately 1.5 is adopted, and the size of the inner and outer slabs is approximately 4.
We tried to unify the size to 9mm square. Thereafter, continuous rolling was carried out in a total of 6 stages for rough rolling and finish rolling to produce a wire rod with a final finished size of φ25 mm. The product yield for molten steel exceeded 99.6%.

[0022]

As described above, according to the present invention, multi-stream casting is possible in a small-section continuous casting apparatus for molten metal in which a mold having an endless grooved ring mold with an open top rotates in the horizontal direction. It is possible to perform consistent continuous rolling at different times, and it is also possible to solve problems caused by differences in casting speed between streams. Furthermore, the method of the present invention enables stable casting and rolling of molten metal, further improving product yield and productivity. Therefore, the present invention is an industrially extremely useful invention that can significantly reduce manufacturing costs.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an outline of a horizontal rotary continuous casting apparatus using an endless groove rotary mold of the present invention.

FIG. 2 shows a cross section taken along the line XX in the casting direction of FIG. 1;

[Figure 3] Casting direction X- when using a casting dummy bar
It is an X sectional view.

FIG. 4 is a process diagram of simultaneous casting and direct rolling of two streams.

FIG. 5 is a process diagram in which each slab is simultaneously rolled between streams in two-stream casting.

FIG. 6 is an explanatory diagram of a rough rolling roll in the case of simultaneous rolling.

FIG. 7 is a method diagram and a roll explanatory diagram for performing finish simultaneous rolling by performing blank pass rolling to compensate for the difference in slab speed due to the difference in slab size in the case of simultaneous rolling.

FIG. 8 is a rolling process diagram in which a dedicated rolling mill for sizing is provided at the front stage.

[Explanation of symbols]

1 Molten metal ladle 2 Molten metal 3 Molten metal injection device 4 Intermediate container 5 Injection amount control means and injection nozzle 6
Endless groove rotary mold 6a Cooling medium channel 7 Solidifying slab 8 Tail weir 9 Tail weir support device 10 Mold rotation means 11 Slab propulsion device 11a Slab propulsion device pressing means 12 Slab propulsion device driving means 13 Knife edge holding Means 14 Slab straightening roll pressing means 15
Slab straightening vertical roll 16 Slab detector 17 Slab straightening horizontal roll 18 Slab 18a Outer slab 18b Inner slab 19 Slab guide roll 20 Slab straightening horizontal roll 20a Roll pressing means 21 Slab detector 22 Cutting machine 23 Knife edge 24 Dummy bar 25 Dummy bar storage device 26 Slab pressing roll 27 Dummy bar split swing frame 28
Unloading roller table 29 Roller table 30 Injection point 31 Scale removal means 32 Slab heating/warming means 33 Rolling roll 34 Product cutting machine 35 Product cooling control means 36 Coiled product 37 Straight product 38 Simultaneous rolling roll 38a Simultaneous rolling roll side 39 Different diameter rough rolling roll 40 Rolled material (thick: inner peripheral side material) 41
Rolled material (thin: outer circumferential side material) 42 Outer circumferential side rolled material cross-sectional area change 43 Inner circumferential side rolled material cross-sectional area change 44 Empty pass rolling roll 45 Sizing material (thick: inner circumferential side material) 46
Empty pass material (thin: outer peripheral side material) 47 Front view of simultaneous rolling rolls 48 Rolled material after sizing 49 Rolled material after empty pass

Claims (4)

[Claims] Claim 1: A continuous casting device for small cross-sections of molten metal in which a ring mold with an open top and an endless groove rotates horizontally. In the case where pieces are simultaneously cast and directly rolled, the concentric groove mold size is defined by the casting speed defined by the radius of each mold as V (m/min), and the cross-sectional area of each slab as S (m2). ) and its product VS (m3/min
) is made to match in all rows. 2. In a small-section continuous casting device for molten metal in which an endless grooved ring mold with an open top rotates horizontally, a plurality of rows of groove molds are provided concentrically on one table, and a plurality of casting molds are formed. When slabs are simultaneously cast and directly rolled, the rolling equipment is a roll, and when rolling multiple slabs at the same time, the diameter of the rolling roll is changed to compensate for the slab speed difference caused by the difference in mold radius, and the circumferential speed is adjusted to the casting speed. A method for continuous casting and rolling of rods and wires, characterized by matching rolling. 3. The casting and rolling method according to claim 1, characterized in that a rolling mill is provided to unify the slab size, and/or slabs with small cross-sectional sizes are blank-pass rolled until the cross-sectional sizes match. Continuous casting and rolling method for rods and wire rods. 4. In a small-section continuous casting apparatus for molten metal in which an endless grooved ring mold with an open top rotates horizontally, one table has one or more rows of groove molds arranged concentrically. In the case of direct rolling after casting, a heating means is provided during the casting and rolling process to heat and/or heat the slab to the rolling temperature.
Or a method for continuous casting and rolling of rods and wires characterized by maintaining high temperatures.